A 36-year-old patient presents several hours after eating tinned fish with a sudden onset of diplopia and dysphagia.
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1. How do you make a diagnosis?
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The diagnosis of botulism is principally made clinically in the presence of a history of suspect-food ingestion. Toxin may be detected in serum and stool but treatment should be instigated on the basis of clinical features.
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2. How is botulism usually acquired?
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Botulism is usually a food-borne disease. Clostridium botulinum multiplies in contaminated food when there is an anaerobic environment (e.g. in canned or preserved food where there heat treatment has been inadequate). Toxin is produced and then ingested.
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3. In what other ways does disease occur?
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There are two other forms of disease – wound botulism, where the organism multiplies in devitalized tissue, and infant botulism, where the organism multiplies in the gut of infants usually around the time of weaning. In both cases the elaborated toxin causes the clinical features of botulism.
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4. How are the symptoms caused?
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The symptoms are caused by botulinum toxins A–G. This causes a descending motor neurone paralysis, which causes respiratory failure that requires ventilation.
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5. What other diseases do clostridia cause?
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Clostridium tetani produces a toxin that causes a spastic paralysis and reflex muscle spasms leading to respiratory failure; Clostridium difficile produces enterotoxins that cause pseudomembranous colitis and diarrhoea, which may lead to bowel perforation; and Clostridium perfringens produces α-toxin that leads to muscle destruction.
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6. What other feature is common to these bacteria that contributes to their epidemiology?
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Many are carried harmlessly in the gut of man and animals so are shed into the environment. They all produce spores that make them resistant to drying and disinfectants. They are also more resistant to heat and therefore more likely to persist in the environment or foods.
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7. How should botulism be treated?
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The patient should be given ventilatory support and specific antitoxin. Penicillin should also be given to prevent the production of more toxin.
